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Patient Directed Recording of a Bipolar Three-Lead Electrocardiogram using a Smartwatch with ECG Function
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An S wave in ECG lead V6 predicts poor response to cardiac resynchronization therapy and long-term outcome
Zeyu Jiang1, Yuanhao Qiu1, Zhiyong Qian1
1Department of Cardiology, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China.
Insights
An S wave in lead V6 predicts poor response to cardiac resynchronization therapy (CRT) in patients with complete left bundle branch block (CLBBB). This ECG finding is linked to worse long-term outcomes, including heart failure rehospitalization or death.
Area of Science:
- Cardiology
- Electrophysiology
- Heart Failure Management
Background:
- Cardiac resynchronization therapy (CRT) is a key treatment for heart failure (HF).
- However, a significant portion of patients (30-50%) do not respond to CRT.
- Identifying predictors of CRT response is crucial for optimizing patient selection.
Purpose of the Study:
- To evaluate the predictive value of an S wave in lead V6 for CRT response.
- To assess the association between specific ECG patterns in complete left bundle branch block (CLBBB) and CRT outcomes.
- To determine if lead V6 S wave presence predicts long-term adverse events in CLBBB patients undergoing CRT.
Main Methods:
- Patients with CLBBB were categorized into three groups based on S waves in leads V5 and V6.
- CRT response was defined as a ≥15% reduction in left ventricular end-systolic volume at 6 months.
- Long-term outcomes, including HF rehospitalization and all-cause death, were analyzed using Kaplan-Meier curves and multivariate logistic regression.
Main Results:
- CRT response rates varied significantly across groups: 85.2% in T-CLBBB, 65.6% in V5S, and 38.5% in V5&V6S (P < .001).
- Patients with S waves in both V5 and V6 (V5&V6S group) showed a higher incidence of HF rehospitalization or death (P < .001).
- An S wave in lead V6 was independently associated with a poor CRT response (HR 0.33, P = .042).
Conclusions:
- An S wave in lead V6 is a significant predictor of non-response to CRT in CLBBB patients.
- The presence of an S wave in lead V6 indicates a poorer long-term prognosis, including increased risk of HF rehospitalization and mortality.
- ECG analysis, specifically the presence of S waves in lead V6, can aid in stratifying CLBBB patients for CRT efficacy.
Background:
Cardiac resynchronization therapy (CRT) is a standard treatment for selected patients with chronic heart failure (HF). However, up to 30%-50% of patients still do not respond to CRT.
Objective:
Our aim was to identify the predictive value of an S wave in lead V6 in CRT response in patients with complete left bundle branch block (CLBBB).
Methods:
The CLBBB definition included the Strauss left bundle branch block criteria and the absence of q waves in leads I, V5, and V6. According to the electrocardiogram at baseline, CLBBB patients were divided into 3 groups: T-CLBBB group (CLBBB without an S wave in lead V5 or V6), V5S group (CLBBB with an S wave in lead V5 and no S wave in lead V6), and V5&V6S group (CLBBB with S waves in leads V5 and V6). CRT response was defined as left ventricular end-systolic volume reduction ≥ 15% at 6-month follow-up. The combined end point included HF rehospitalization or all-cause death.
Results:
Of 181 patients with left bundle branch block-like pattern, 112 patients with CLBBB were included into 3 groups: 54 in the T-CLBBB group, 32 in the V5S group, and 26 in the V5&V6S group. The CRT response rate was 85.2% (46), 65.6% (21), and 38.5% (10), respectively (P < .001). Kaplan-Meier curves demonstrated that patients in the V5&V6S group had a higher incidence of HF rehospitalization or all-cause death than those in the other 2 groups (P < .001). In a multivariate logistic regression model analysis, an S wave in lead V6 was significantly associated with CRT nonresponse (hazard ratio 0.33; 95% confidence interval 0.11-0.96; P = .042).
Conclusion:
An S wave in lead V6 can predict poor response to CRT and long-term outcome.
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